Polymeric Coatings Overview - Cal Poly, San Luis Obisporhfernan/chem550/pdf/Chem550... ·...
Transcript of Polymeric Coatings Overview - Cal Poly, San Luis Obisporhfernan/chem550/pdf/Chem550... ·...
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Polymeric Coatings Overview
CHEM 550, Spring 2006Ray Fernando, Cal Poly - SLO
Polymeric Coatings Overview
Coating Process – Life CyclePVC, CPVC, NVVChemistry, Function of IngredientsCoating Types – Waterborne, Solvent-Based, High-Solids
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COATINGS ARE USED FORCOATINGS ARE USED FOR……Aesthetics
Decoration, Camouflage, MarkingsTexture
Substrate ProtectionCorrosion Resistance, Wear, Impact
Specialty FunctionsOptical, Electromagnetic, Insulation (Electrical, Thermal), Absorption (Sound), Conductive
CoatingsScience
Polymer Science
Color & Appearance
Rheology
EnvironmentalScience
Colloid & InterfacialScience
Mechanics
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Coating Formulation IngredientsCoating Formulation IngredientsBinders
WaterborneSolvent based
PigmentsHidingColor
FillersAdditives
B
B
BB
BC
C
C
C
C
A A
A
A
A
A A
ABinder
Vehicle
Pigment/Filler
Wet Coating Wet Coating FormulaionFormulaion
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Dry Coating FilmDry Coating Film
Binder
Dry Film – Clear Coat
Pigment/Filler
Binder
Dry Film – Pigmented Coat
Example I: MidExample I: Mid--Quality Interior Wall Quality Interior Wall PaintPaint
Shelf life > 1 year, heat age and freeze-thaw stableSelling price, < $20/galApplication by home owner Do-It-Yourself (DIY)
Brush and roller
Easy application, quick dry at 70oFApplication over old paint, minimum surface preparationLow solvent, low odor, easy clean-up
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MidMid--Quality Wall Paint Quality Wall Paint RequirementsRequirementsColor and hiding powerLow glossScrub resistance and cleanability3-4 years service lifeEasy touch-up, good color match
Example II: Aircraft TopcoatExample II: Aircraft TopcoatShelf life: > 1 year, heat age and freeze-thawCost - $100/galSpray application at airframe manufacturer or depot by professionalPot life > 4 hrs (at temperatures up to 90oF)Dry time at temperatures from 50 to 90oF:
Dry to remove tape: < 4 hrsDry hard: < 6 hrs
Application over epoxy primer
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Formulating StrategyFormulating StrategyI. Define Requirements During Coatings’
Life CycleRaw MaterialsMixing and BlendingStorageApplicationDrying / CuringShipping / InstallationProduct LifeDisposal
Interior Flat Wall Paint FormulationInterior Flat Wall Paint FormulationMATERIAL Pounds Gallons NVM-Lbs. NVM-Gals.
GRIND3.0% Cellulosic Thickener Solution 50.0 6.00 1.5Water 120.0 14.41Dispersant, 35% T.S. 8.0 0.81 2.8Surfactant 2.6 0.33Buffer 2.0 0.23Defoamer 2.0 0.27Preservative 1.0 0.12TiO2, Flat Grade 125.0 3.91 125.0 3.91Calcined Clay 175.0 9.55 175.0 9.55Calcium Carbonate 175.0 7.75 175.0 7.75SUB-TOTAL: 660.6 43.38 475.0 21.20 Grind to 4+ H.S.
LET-DOWN3.0% Cellulosic Thickener Solution 200.0 24.01 6.0Water 0.0 0.00
LATEX ADD:Vinyl Acrylic Polymer (55.0%) 201.0 22.21 110.6 11.42Defoamer 2.0 0.27Propylene Glycol 26.0 3.02Texanol 8.0 1.01Water 51.0 6.12 TOTAL 1148.6 100.03 585.6 32.62
PHYSICAL PROPERTIES
Wt./Gal.: 11.5% Solids, By Weight: 51.0% Solids, By Volume: 32.6% PVC: 65.0% PVC, TiO2: 12.0% Disp. Solids On Pigment: 0.6% C.S. on Latex NVM: 7.2
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Aircraft Topcoat FormulationAircraft Topcoat FormulationMaterial Pounds Gallons NVM-lbs NVM-Gals(Component A)Polyester polyol 238.0 29.9 200.0 50.0
(84% solids)Titanium dioxide 549.4 17.0 549.4 17.0DBTD catalyst 10.0 1.5 1.0 0.1
(1% in MEK)Surfactant 10.0 1.5 1.0 0.1
(1% in MEK)MEK 177.4 26.1 0.0 0.0
(Component B)Isocyanate 233.0 24.0 174.8 18.0
(75% solids)
TOTAL 1217.8 100.0 926.2 85.2
% solids, weight 76.1% solids, volume 85.2% PVC 20.0VOC, lbs/gal 2.6NCO/OH 1.1
HegmanHegman Grind GaugeGrind GaugeHegman
ScaleDepthin mils
012345678
0.50
1
2
3
4
1.5
2.5
3.5
Equivalent inmicrons
12.50
25
50
75
100
37.5
62.5
87.5
scraper
reading
dispersion
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Important Paint Formulation Important Paint Formulation ParametersParameters
Pigment volume concentration (PVC)Critical pigment volume concentration (CPVC)Solids content; non-volatile volume (NVV)Volatile organic compounds (VOC)CostStoichiometryVolume mix ratios (2 component coatings)
B
B
BB
BC
C
C
C
C
A A
A
A
A
A A
ABinder
Vehicle
Pigment/Filler
Volume solids (Non Volatile Volume Volume solids (Non Volatile Volume -- NVV)NVV)
%NVV = Volume of binder + Volume of pigment
Total volume of wet paintx100
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Pigment Volume Concentration (PVC)Pigment Volume Concentration (PVC)
PVC is the ratio, by volume, of allpigments & Filler
in the coating to total non-volatiles
Filler
Binder
Dry Film
PVC = Volume of (Pigment + Filler)
Total Volume of Dry Coating
Critical Pigment Volume Critical Pigment Volume Concentration (CPVC)Concentration (CPVC)
CPVC = the PVC where there is just sufficient binder to coat pigment surfaces and fill the voids between pigment particles.
At CPVC striking changes are observed in the properties and behavior of paint films.
Filler
BinderDry Film
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Critical Pigment Volume ConcentrationCPVC
PVC = 0 PVC > CPVC PVC = 1.0PVC = CPVCPVC < CPVC
PigmentBinder
( ) ( )VolumeBinderVolumePigmentVolumePigment
PVC+
=
Properties that change abruptly at Properties that change abruptly at the CPVCthe CPVC
Optical PropertiesLight scatteringHiding power efficiencyGloss / Sheen
Others PropertiesElectrical conductivityBlock resistance
Physical PropertiesDensityTensile Strength
Permeability Properties
PorosityBlistering
DurabilityWet Scrub ResistanceStaining
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Pigment Volume Effects on Dried Paint Pigment Volume Effects on Dried Paint
CPVC
Factors That Effect Packing Efficiency
1. Particle Size Distribution 2. Particle Shape or Shape Distribution
CPVC Depends onCPVC Depends onthe Packing Efficiencythe Packing EfficiencyPigments within BinderPigments within Binder
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Factors Determining CPVCFactors Determining CPVCParticle PackingParticle Packing
High PVC Low PVC
Factors Determining CPVCParticle Size - First Approximation
Q - Which packs more densely - large or small circles?
A - Void fraction the same in each case
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Factors Determining CPVCFactors Determining CPVCParticle Size Particle Size -- Other ConsiderationsOther Considerations
particle minimum layerof binder
Coated particle is 70% binder Coated particle is 30% binder
Also: Small particles pack less densely
Factors Determining CPVCFactors Determining CPVCParticle Dispersion Particle Dispersion -- TiOTiO22 in Mineral Oilin Mineral Oil
0.000.050.100.150.200.250.300.350.400.450.50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Dispersant Level
CPV
C
Asbeck, JCT 49, 635, 59 (1977)
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Factors Determining CPVCParticle Porosity
Diatomaceous Earthan empty sphereCPVC = 0.18
Fumed Silicavery open structureCPVC = 0.23
Oil Absorption (OA) ValueOil Absorption (OA) ValueGrams linseed oil required to form a paste from 100 gram pigment.Oil first coats surface and fills voids; excess needed to turn moist solid into liquid.Depends on:
Surface area / Particle size (like CPVC)Packing - presence of voids / porosity (like CPVC)Wettability
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Significance of OA
Rough guide to surface area (dispersant demand, adsorption of other materials from liquid paint).Also, OA is related to cpvc …
% void fraction:• OA if oil• CPVC if resin
OA / CPVC Relationship:
[ ]( ) ⎟⎠⎞⎜
⎝⎛ ⋅+
=
5.931
1ρOA
cpvc
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Particle ShapeParticle ShapeMaterial Size, μm Shape
Titanium dioxide
Calcium Carbonate
Ground
Precipitate
Clays
Ground
Calcined
Silica
Diatomaceous
Talc
Mica
0.2 - 0.5
0.6 - 20
0.1 - 2
0.1 - 5
0.8 - 2
4 - 10
1 - 10
8 - 50
block
block
block, aggregates
plate
plate
irregular
plate and fiber
flake
Coating Life CycleCoating Life Cycle
Raw MaterialsMixing and BlendingStorageApplicationDrying / CuringShipping / InstallationProduct LifeDisposal
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Mixing and BlendingMixing and BlendingEase of additionOrder of AdditionEase of MixingHeat build-upFoamingShockingHealth & SafetyOdorDelivery to Storage / Use TankClean up
StorageStorageFreeze-Thaw StabilityHeat StabilitySettling of componentsPhase SeparationGel-FormationSpoilage
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ApplicationApplicationProfessional painter vs home ownerApplication Environment
Controlled (OEM) vs or On-siteInterior vs Exterior)
Method of applicationroller, slide, slot, blade, curtainbrush, spray, etc.
Delivery to ApplicatorRequired film thicknessSubstrate
Cleanliness, texture, porosityWaste and RecyclabilityEnvironmental regulations
Drying/CuringDrying/CuringDrying Conditions
Controlled (OEM) vs or On-siteInterior vs Exterior)
Sag and LevelingSubstrate Constraints
Temperature LimitsWarp
DefectsAdhesionEnvironmental regulations
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Product LifeProduct LifeAppearance
Color, gloss, opacityMechanical Properties
Hardness, flexibility, scrub resistanceSubstrate Protection
Corrosion, wearChemical Resistance
Stain, acid, baseEmissions
Indoor air qualityTouch-up and Refinish
Coating IndustryCoating Industry
33%27%
22%18%
Europe North America Asia Other
Total Value - $70.6 billion
Total Volume - 5 billion gal.
34%30%
21% 15%
Europe North America Asia Other
Global Coating Market Global Coating Market –– Yr 2000Yr 2000Current Current –– Approx. $80 billionApprox. $80 billion
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Coating Market Segments Coating Market Segments -- USUS
OEM Product CoatingsAutomotiveMarineAircraftMetal ContainersAppliancesMachinery and EquipmentWood FurniturePlasticsCoilOverprint
Architectural PaintsInteriorExterior
Special PurposeIndustrial MaintenanceTraffic PaintAuto Refinish
MiscellaneousRoof, Tank, DeckConcrete
Penetration of Waterborne Penetration of Waterborne Coatings Coatings –– US US
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% Penetration (1985)
41Special Purpose Coatings
80Architectural Paints
26OEM Product Coatings
% Penetration (2000)
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Resin/BinderProducers
AdditiveProducers
Distributors andResellers
ContractorsApplicators
Distributors andResellers
Spcifiers/End- Users
Solvent Producers
Pigment Producers
SpecialtyIntermediates
Formulators
Inspectors
Equipment
COATINGS INDUSTRY STRUCTURECOATINGS INDUSTRY STRUCTURE